A Comprehensive Guide to Local Exhaust Ventilation for Welding

Welding, a critical process in manufacturing and construction, poses significant health risks due to the hazardous fumes it generates. These fumes, composed of various metals and gases, can lead to severe health issues, including respiratory problems, neurological damage, and even cancer. Given these dangers, the importance of effective fume extraction cannot be overstated.

Local Exhaust Ventilation (LEV) systems are pivotal in mitigating these risks. By capturing fumes at their source and removing them from workers’ breathing zones, LEV systems ensure a safer welding environment, protecting workers’ health and complying with occupational safety standards.

Principles of Local Exhaust Ventilation

Explanation of How LEV Systems Work

Local Exhaust Ventilation (LEV) systems are designed to remove harmful fumes and dust at their source, preventing them from entering workers’ breathing zones and the wider workplace environment.

These systems operate on the principle of capturing contaminants close to their generation point and safely transporting them away for filtration and discharge. By doing so, LEV systems play a crucial role in maintaining air quality and protecting worker health in environments where hazardous substances are present.

Components of an LEV System

• Vacuum Unit: Acts as the heart of the system, generating suction to capture welding fumes efficiently.
• Dust Collector: Filters and collects the extracted particulates and fumes. It may be a separate unit in stationary systems or integrated with the vacuum unit in portable systems.
• Ventilation Network: Comprises ducts and hoses that transport fumes from the extraction point to the dust collector. While portable units often use a simple hose, stationary systems might employ a complex arrangement of ducts and hoses.
• Extraction Tools: Include various devices like flexible arms, MIG extraction guns, nozzles, and hoods designed to capture welding fumes at the source.

Types of LEV Systems Used in Welding

Low-Vacuum/High-Volume vs. High-Vacuum/Low-Volume

The choice between low-vacuum/high-volume and high-vacuum/low-volume systems depends on the specific welding operations and the types of extractors used.

Low-vacuum/high-volume systems are suited for capturing fumes over a larger area with less precise extraction points, making them ideal for fume extraction arms or hoods.

High-vacuum/low-volume systems, on the other hand, are designed for targeted fume extraction as close to the welding pool as possible, which is particularly effective with fume extraction MIG guns and nozzles.

For a more information, please read our detailed comparison.

Portable vs. Stationary:

The decision between portable and stationary LEV units hinges on the needs of the welding environment.

Portable units are flexible and suitable for locations where welding tasks vary or occur in different areas, usually with less than five welders. They can be easily moved to where they are most needed.

Stationary units, conversely, are fixed and typically serve dedicated welding stations where operations are constant. They are often more powerful and can handle higher volumes of fumes. They tend to be more cost-efficient whenever there are more than five welders.

For insights into the pros and cons of each, refer to Henlex’s overview on mobile vs. stationary fume extraction units.

Designing an Effective LEV System

Factors to Consider When Designing an LEV System for Welding Operations

When selecting a suitable welding fume extractor, it’s essential to consider various factors, including the welding process, the type of technology ideal for that process, and the environment in which the welding occurs. The best extractors and technology, depending on the welding process, are presented in the table below.

Process	MIG gun	Arm	Nozzle	Hood	Table
Technology	HVLV	LVHV	HVLV	LVHV	LVHV
Mobile vs Stationary	Both	Both	Mobile	Stationary	Stationary
MIG / GMAW	Best	Yes	Yes	No	No
TIG / GTAW	No	Best	Yes	No	No
Fluxed-Cored / FCAW	Best	Yes	Yes	No	No
Stick / SMAW	No	Best	Yes	No	No
Robotic Welding	Yes	Yes	No	Best	No
Aluminum Welding	Best	Yes	Yes	No	No

The Importance of Capture Velocity

Capture velocity is crucial for the LEV system’s efficiency and refers to the speed at which air must move at the opening of an extraction point to capture contaminants effectively. Minimum recommended airflow rates to get the appropriate velocity for various extraction tools are as follows:

• Fume extraction MIG gun: 100 cubic feet per minute (cfm)
• 3″ fume extraction arm: 200 cfm
• 4″ fume extraction arm: 300 cfm
• 6″ fume extraction arm: 600 cfm
• 8″ fume extraction arm: 900 cfm (though generally not recommended due to space and cost considerations)
• 2″ fume extraction nozzle: 200 cfm
• 3″ fume extraction nozzle: 300 cfm
• 4″ fume extraction nozzle: 400 cfm

The vacuum unit must be able to provide this operating airflow to all the stations simultaneously. It is crucial to consider the pressure drops in the system and not just look at the unit’s maximum airflow (with no pressure drops).

Sizing and Positioning of Extractors for Optimal Performance

Proper sizing and positioning are essential for the effectiveness of the LEV system. While the positioning of a fume extraction MIG gun is typically straightforward and close to the source of fumes, other extractors require strategic placement.

A general rule is to position the extractor about three times the diameter of the extraction hood above (or one time the diameter behind) the weld pool for optimal capture efficiency. This ensures that fumes are effectively captured without disrupting the welding process or compromising worker safety.

The best way to get the proper positioning is by trial and error. You must find a position that enables a perfect fume extraction without disrupting your operations.

In general, we also recommend extracting as close as possible to the source and using the smallest extraction tool possible.

Any questions? Ask them directly in the chat at the bottom right of your screen or during one of our webinars.

Installation and Maintenance of LEV Systems

Guidelines for the Proper Installation of LEV Systems

The correct installation of Local Exhaust Ventilation (LEV) systems is crucial for their effectiveness in capturing and removing hazardous welding fumes. Key considerations include:

• Assessment of Welding Processes: Before installation, assess the specific welding processes and materials to ensure the LEV system is appropriately tailored. This assessment helps choose the right type of system (e.g., LVHV or HVLV) and components (e.g., MIG gun, extraction arms, hoods) for effective fume extraction.
• Workshop Layout and Space: Consider the physical layout of the workspace and the placement of welding stations. The LEV system should be designed to integrate seamlessly without obstructing workflow. Enough space should be allocated for the system’s components, including the ductwork and filtration units, allowing easy access for maintenance and adjustments.
• Capture Zone Design: The design of the capture zone, where the system initially captures fumes, is critical. Ensure that the extraction points are positioned as close as possible to the source of fumes without interfering with the welding operation.
• Airflow and Exhaust Considerations: Proper airflow is essential for effectively operating an LEV system. The system should provide sufficient airflow to capture and transport fumes, considering factors like pressure drops and the need for make-up air to prevent negative pressure in the workspace.
• Compliance with Regulations: Ensure that the LEV system meets all relevant local and national regulations regarding air quality and occupational health and safety. This includes adherence to standards for exposure limits, ventilation system design, and emission controls.
• Energy Efficiency: Consider the energy consumption of the LEV system. Efficient systems can significantly reduce operating costs. Look for features like soft starts, automatic ON/OFF functionality, automatic valves, smaller motors, etc.
• Noise Levels: The operation of LEV systems can contribute to workplace noise. Selecting systems to minimize noise or implementing noise reduction measures can help maintain a more comfortable and compliant working environment.
• Installation by Qualified Professionals: Ensure that experienced and qualified professionals install the system. Proper installation is crucial for the system’s effectiveness, safety, and regulation compliance.
• Future-Proofing: Consider the potential for future changes or expansions in welding operations. Designing the LEV system with flexibility for modifications can help accommodate new processes or increased capacity.

• Ducting Gauge: For High-Vacuum/Low-Volume (HVLV) systems, where the pressure is relatively high, it’s essential to use thicker ducting to withstand the system’s demands. The gauge of the ducting should be selected based on the system’s specifications to ensure durability and performance.
• Filter Selection: Using filters with a Minimum Efficiency Reporting Value (MERV) of 13 or higher is recommended to capture fine particulates from welding fumes effectively. For more information on choosing the right filter, visit Henlex’s guide on MERV ratings.

Routine Maintenance and Inspection Schedules

To ensure the LEV system continues to operate efficiently, a routine maintenance and inspection schedule should be established:

• Daily and Weekly Checks: These may include visual inspections of the system, checking for duct blockages, and ensuring the filters are not clogged. Filters should be replaced or cleaned according to the manufacturer’s guidelines.
• Monthly and Quarterly Reviews: More in-depth checks of the system’s components, such as the fan, motor, and electrical connections, should be conducted.
• Annual Audits: A qualified professional’s comprehensive review of the system can help identify any wear and tear or adjustments needed to maintain optimal performance.

For detailed maintenance practices, refer to Henlex’s maintenance best practices.

Troubleshooting Common Problems in LEV Systems

Even with regular maintenance, LEV systems may encounter issues. Common problems and their solutions include:

• Reduced Suction: This may be due to clogged filters or duct blockages. Regularly replacing or cleaning filters and clearing any obstructions can resolve this issue.
• Noisy Operation: Excessive noise could indicate problems with the fan or motor. Inspection and repair by a professional may be necessary.
• Inefficient Fume Capture: If the system fails to capture fumes effectively, reevaluating the positioning of the extraction arms or hoods, as well as checking for leaks in the ductwork, may be required.

For a comprehensive troubleshooting guide, visit Henlex’s troubleshooting guide for welding fume extraction.

General Ventilation for Welding: What are the Rules?

For welding ventilation, the general rule is to aim for 4 air changes per hour in an industrial environment, including air exhausted by welding fume extractors. This guideline is commonly recommended by occupational safety organizations like OSHA in the United States and CNESST in Quebec.

In confined spaces, it’s advisable to increase the air changes per hour to a minimum of 10, combined with an efficient source extractor, to ensure a safer breathing environment.

Creating a Culture of Safety

The Importance of Training and Awareness for Welding Personnel

Training and awareness are pivotal in ensuring welding personnel understand the risks associated with welding fumes and the importance of using LEV systems. Regular training sessions can educate workers on the correct use of LEV equipment and the procedures to minimize exposure to hazardous fumes. This knowledge empowers employees to take an active role in maintaining their health and safety.

Integrating LEV Systems into Workplace Safety Programs

Incorporating LEV systems into comprehensive workplace safety programs is crucial. This integration should include clear policies on system use, maintenance schedules, and regular checks to ensure the LEV systems are functioning correctly. By embedding these systems into the safety culture, organizations demonstrate a commitment to worker health and regulatory compliance, fostering a safer work environment.

Encouraging a Proactive Approach to Health and Safety in Welding Operations

Promoting a proactive approach to health and safety encourages employees and management to anticipate potential hazards and take preemptive action to mitigate risks. This approach includes regular risk assessments, feedback loops for safety concerns, and continuous improvement practices to enhance safety measures, including the effective use of LEV systems.

Understanding Welding Fumes

Composition of Welding Fumes and Gases

Welding fumes are a complex mixture of metallic oxides, silicates, and fluorides. These fumes are generated when a metal is heated above its boiling point, and its vapors condense into submicronic particulate matter. The specific composition of welding fumes can vary depending on the materials being welded and the process used. Typical components of welding fumes include:

• Aluminum, Antimony, Arsenic, Beryllium, Cadmium, Chromium, Cobalt, Copper, Iron, Lead, Manganese, Magnesium, Molybdenum, Nickel, Selenium, Silver, Tin, Titanium, Vanadium, Zinc.
• Argon, Carbon Dioxide, Helium, Carbon Monoxide, Hydrogen Fluoride, Nitric Oxide, Nitrogen Dioxide, Ozone, Phosgene

Health Risks Associated with Welding Fumes

The inhalation of welding fumes and gases can lead to a wide range of health issues, including:

• Eye, nose, and throat irritation
• Dizziness and nausea
• Breathing difficulties, potentially leading to suffocation or asphyxiation
• Metal fume fever
• Lung damage and asthma
• Various types of cancer, including lung and kidney cancer
• Stomach ulcers and kidney damage
• Neurological issues, including manganism
• Skin conditions like dermatitis or eczema
• Bone and joint disorders
• Specific conditions associated with the inhalation of certain metals, such as welder’s lung, aluminosis, siderosis, stannosis, anthracosis, and berylliosis
• Accumulation of fluid in the lungs

Regulatory Standards for Exposure Limits

To protect workers from the harmful effects of welding fumes, regulatory bodies have established exposure limits:

• USA: The exposure limit is 5mg/m³ for general fumes. For more details on US regulations, visit our page about US exposure limits.
• Canada: Exposure limits vary by province, ranging from 5mg/m³ to 3mg/m³ for respirable particles and up to 10mg/m³ for inhalable particles. For comprehensive information on Canadian standards, refer to our Canadian welding fume regulations page.

Many fume components also have their exposure limits in the US and Canada. They can be found in the link articles.

Conclusion

Implementing Local Exhaust Ventilation (LEV) systems is a critical component in safeguarding welders from the dangers of hazardous fumes. These systems play a vital role in creating a safer working environment by effectively capturing and removing contaminants at their source. However, the effectiveness of LEV systems extends beyond their installation. It requires a commitment to regular maintenance, proper use, and ongoing safety training.

By investing in efficient fume extraction solutions and prioritizing the health and safety of workers, organizations can significantly reduce the risks associated with welding operations, ensuring a healthier workplace and compliance with occupational health standards.